Why Is East-West Traffic Important in ISP Networks?

Why Is East-West Traffic Important in ISP Networks?

The terms east-west traffic and north-south traffic are pivotal for understanding data flows. These concepts are not limited to data centers or enterprise networks; they also have significant implications in Internet Service Provider (ISP) networks. While ISPs primarily focus on external connectivity (north-south traffic), the importance of east-west traffic within their networks is growing as services evolve and customer expectations increase.

This blog post explores the role of east-west traffic in ISP networks, its challenges, and how ISPs can optimize it to meet modern demands.


What Is East-West Traffic in an ISP Network?

In an ISP network, east-west traffic refers to the movement of data between internal systems, such as between:

  • Regional Points of Presence (PoPs): Data traveling between regional nodes or hubs.
  • Caching Servers: Content shared among CDN (Content Delivery Network) nodes for efficiency.
  • Internal Network Services: Communication between ISP-managed services like DNS servers, authentication systems, and management platforms.

This contrasts with north-south traffic, which handles the data flow between the ISP network and its external customers or upstream providers.

Examples in ISPs:

  • A customer in one region accesses cached video content stored in another region.
  • Internal system updates propagated across multiple ISP nodes.
  • Inter-regional traffic for VoIP or other latency-sensitive services.
  • Customers existing different data centers because of BGP traffic engineering.

Why Is East-West Traffic Important in ISP Networks?

1. Content Delivery Optimization

Modern ISPs often deploy CDN nodes to cache popular content locally, reducing latency for end users. However, these CDN nodes need to synchronize data, generating east-west traffic. Efficient internal traffic handling, like streaming videos or software updates, ensures faster content delivery. ISPs can exchange traffic on Internet Exchanges (IX) to optimize traffic delivery. Larger ISPs can also deploy internal cache nodes close to their customers.

2. Reliability and Redundancy

ISPs maintain robust failover mechanisms to ensure network uptime. When a node experiences issues, traffic may reroute to another node, often within the ISP’s infrastructure, increasing east-west traffic temporarily. Proper management ensures minimal service disruption. Everything from load on devices on the network to the type of media to route miles can influence this.

3. Internal Network Services

Critical services such as DNS lookups, DHCP, and AAA (Authentication, Authorization, and Accounting) often involve east-west communication. Ensuring these services operate efficiently is key to maintaining customer satisfaction. Having these as close to the customer can increase the time it takes to make it to the customer. This can be rolled into the concept of edge computing.

A clean and simplified infographic showing east-west traffic in an ISP network. The image includes essential elements such as routers, switches, servers, and data centers, connected with clear, bold lines and minimal arrows to indicate traffic flow. Focus on a modern, streamlined design with fewer components, using a subtle technological background with a light grid or simple abstract patterns. Use a minimal color palette of blue, green, and gray tones for a professional and uncluttered look.

Challenges of East-West Traffic in ISP Networks

1. Scalability

As ISPs grow, the volume of east-west traffic can increase exponentially. Without scalable infrastructure, bottlenecks may form, leading to degraded performance. In remote areas, capacity and diversity can be challenging. Getting enough bandwidth for redundancy is usually demanding, especially in rural or remote areas.

2. Latency

High east-west latency can impact user experience in services like VoIP or gaming. ISPs must design networks to minimize hops and delays. Large geographic areas should be optimized to reduce the physics of fiber or microwave hops.

3. Security

While most security measures focus on north-south traffic, unmonitored east-west traffic can expose the network to threats like lateral movement by attackers. Implementing security measures internally is critical. Many network operators forget attacks can come from within. Too many times, these ISPs are just worried about attacks from hosts on the public Internet. They forget customer devices can be compromised and taken over.

4. Bandwidth Management

East-west traffic competes with north-south traffic for bandwidth. Balancing these flows requires advanced traffic engineering techniques. This is especially true if links are unbalanced. For example, a fiber route that is 50 miles longer than another can introduce more latency if that path becomes the primary.


Solutions for Managing East-West Traffic

1. Traffic Engineering

Using technologies like Multiprotocol Label Switching (MPLS) or Segment Routing (SR), ISPs can dynamically route east-west traffic to avoid congestion and optimize paths. Solutions such as Preseem can help in ISP networks.

2. Network Function Virtualization (NFV)

NFV allows ISPs to deploy virtualized network services closer to where they’re needed, reducing east-west traffic across longer distances and improving responsiveness.

3. Enhanced Caching

Optimizing caching mechanisms reduces the need for east-west data synchronization. Technologies like hierarchical or distributed caching can improve efficiency. As Data needs increase deploying content closer to the customer is becoming a priority.

4. Microsegmentation

Implementing microsegmentation for internal traffic reduces the risk of lateral movement in case of a breach. This is particularly important for securing east-west flows between nodes.

5. Observability Tools

Monitoring tools help ISPs track east-west traffic patterns, identify bottlenecks, and ensure efficient resource usage.


East-West Traffic in Emerging ISP Architectures

1. Modern Networks

In modern networks, east-west traffic is critical in communication between base stations, edge nodes, and central cores. Efficient handling ensures low-latency services. Lower latency switches, protocol compacting, and even the length of cables are being considered. ISPs are taking lessons from the High-Frequency stock and securities traders.

2. Cloud-Integrated ISPs

Many ISPs now integrate with public cloud platforms, creating hybrid models where internal traffic must traverse between on-premises systems and cloud-based services.

3. IoT (Internet of Things)

IoT devices often generate localized east-west traffic for syncing and local processing, necessitating edge-based optimizations. Vast amounts of data can be generated from your typical home. Thermostats and home automation are just two sectors generating massive amounts of data, which usually have to go up to the cloud.


The Future of East-West Traffic in ISP Networks

As services become more distributed and latency-sensitive, managing east-west traffic will only grow in importance. ISPs need to:

  • Invest in advanced routing and switching infrastructure. things like deep buffers and low latency architectures become more and more important
  • Prioritize internal traffic security alongside external threats.
  • Leverage automation for real-time traffic management. Being able to re-route segments of traffic in real-time can increase efficiencies.
  • Collapsing the stack. Running fewer protocols in your networking stack can increase efficiency and latency. Protocols like eVPN are rapidly finding their way into service provider networks.

Conclusion

While east-west traffic is often overshadowed by the more visible north-south traffic in ISP networks, its importance cannot be overstated. Whether enabling smooth content delivery, supporting edge computing, or ensuring reliable services, managing east-west traffic efficiently is key to delivering the seamless experiences that modern customers expect. As technology advances, ISPs that optimize their internal traffic flows will stand out in the competitive connectivity landscape.

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